DE3305852A1 - Two-stroke diesel engine with opposed free pistons - Google Patents

Abstract

In the case of a two-stroke diesel engine with opposed free pistons 2 and hydraulic pump 3 the reciprocal movement of the free pistons with complete balancing of masses in each cylinder is converted into rotary motion by the hydraulic oil delivered by the hydraulic pump or pressurised water by means of a hydraulic motor and/or a free jet turbine. On the return of the free pistons, the acceleration is largely produced by the air compressed in the buffer chambers of the free pistons. Instead of the hydraulic piston connections previously indicated, compressed air piston connections are now proposed, because in this case the pressure losses and the acceleration pressures are lower and the ducts 15 between each two cylinders are smaller and simpler. For the high piston speeds, nozzle cone valves are proposed for the pressure valves 31 and the intake valves 32 of the hydraulic pump, which cone valves have a low pressure loss owing to a heavy reduction of the high cracking speed in the expanded nozzle behind the valve seat associated with an increase in pressure. Starting is by way of a starter injection pump 11 with two pump pistons and starter compressed air valve 12 so that each cylinder has a starter injection. <IMAGE>

Description

Two-stroke diesel engine with counter-rotating pre-piston

In the two-stroke Biesel engine with counter-rotating free pistons Äe ^ ertWHeeiaeBepeepeBPBBWP ^ is the stroke movement of the free piston with complete mass balance in each cylinder through that of the direct; powered hydraulic pump, pumped oil or Pressurized water with a hydraulic motor or with a counter-pressure free jet turbine transferred in rotary motion.

The proposed two-stroke diesel engine has in each cylinder two counter-rotating free pistons that have a thin pump piston on the inside and form a buffer chamber with the pump cylinder. In addition, two cylinders at each end have a piston connection through channels, so that the pressure oil delivery with the same ignition interval runs evenly.

The opposite. Free piston delayed by the buffer pressures and are accelerated, are maintained in a steady state by the buffer pressures.

Due to the counter-rotating free pistons, the engine has a complete Mass balance, a direct current flush without valves, low. Friction losses and low. 'Heat losses. In addition, the free pistons have simple piston ring seals and are in the water-cooled cylinders through the water of the Piston connections and the buffer air well cooled. The purge air is supplied by an exhaust gas turbocharger. A complete injection pump belongs to each cylinder Compression drive.

The injection pump is regulated automatically. by the Load-dependent delivery pressure of the hydraulic pump.

The injection pumps arranged above the compression chambers are switched on and off by a switch rod also connected by lines to the starter compressed air valves and the starter injection pump.

By tangential injection with a single-hole injection nozzle In the compression chamber, the air charge circulating in the same direction results in good mixture formation and complete combustion achieved

With a control range of 16 to 200 bar ', the pressure air vessels the hydraulic pump at the minimum pressure by spring-loaded Piston valves shut off, so only small pressure air vessels

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The invention "consists in improvements to the piston connections, the pump valves and the ^ starting

According to the invention, the piston connections with "water and pressure, air filled, so that when the two free pistons fall in one cylinder only compressed air through small channels in the other Cylinder is displaced.

This design has the advantage that at the strong acceleration the free piston does not rise sharply due to the gas pressure, the pressure in the piston connections, and that at low pressure. the two cylinders lose small connecting ducts Have pipes.

According to the invention, nozzle cone valves are proposed for the pressure and suction valves of the hydraulic pump, which have a nozzle-shaped widened gap behind the valve seat, in which without . Pressure loss the high splitting speed is greatly reduced when the pressure rises.

When closing, the impact effect of the valve cone is caused by the strong pressure increase in the case of the water displacement in the valve seat, which takes place with increasing gap speed. According to the invention, the starting device consists of a compressed air-driven starter injection pump with two pump pistons, which are connected to the injection pumps through lines Starting compressed air valves are connected, and the starting piston valves, which only work at pressures of 6 or 8 bar in one Cylinder pair open the starter injection lines so that the injections in these cylinders have a favorable distance. After this impact, the free pistons take place at high compressions normal injections and the start valves of the pump cylinders are closed.

By the low. The hydraulic pump, which is driven directly by the free piston, has high pressure losses in the nozzle cone valves Efficiency.

With the high efficiency of the hydraulic pump and a back pressure free jet turbine is at the low. Heat losses of the two-stroke diesel engine with counter-rotating free pistons affect the overall efficiency the combination with a back pressure free jet turbine is greater than the efficiency of a four-stroke diesel engine.

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In addition, the simple design has no crank mechanism and Cylinder head at delivery pressures of 200 bar and piston speeds of 30 to "15 m / s at the high speed of a back pressure free jet turbine the power to weight ratio is much lower. , .- ^ The proposed Drives are suitable for vehicles, ships, Conveyors, pumps, compressors and power generators. When the load is low, the diesel engine is partially operated Saves fuel.

In the drawing, the invention is shown, for example, namely shows

Sheet 1 a horizontal longitudinal section "2" vertical longitudinal section
". 3 *" cross section

a two-stroke diesel engine with counter-rotating free pistons ¹¹ 4 · an injection pump with compression drive ^ ~ ¹¹ 5 "starter injection pump with compressed air drive" 6 a longitudinal section through two nozzle cone valves of the hydraulic pump.

The basic form of these engines consists of two cylinders 1, each with two free pistons 2 rotating in opposite directions, with thin pump pistons 4-der externally arranged hydraulic pumps 3 are connected. • The pump cylinders penetrating into the free pistons also serve as a buffer piston 5 and form in the interior of the four free pistons four buffer chambers P, through which the free pistons are decelerated to the outside and accelerated to the inside. Through the connecting channels at the ends of the two cylinders, the free pistons also have a compressed air piston connection, Thus, with the same ignition interval, the pressurized oil or pressurized water delivery runs evenly.

Due to the high pressures of the air in the outer end positions of two counter-rotating free pistons in the two buffer chambers

may occur an uneven shift of the same time free pistons accelerated by the gas pressure do not occur;

With simple piston ring seals, the free clips in the water-cooled cylinders have the buffer air and the water in the Compressed air piston connections provide effective cooling.

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The motor works with a direct current purging without valves " The inlet slots E and outlet slots A located at the outer stroke ends of the free pistons are hereby the free pistons controlled.

The scavenging air is from the exhaust gas turbocharger 40 through the charge air line 42 is pressed into the cylinder and displaces the remaining exhaust gas into the exhaust pipe 41.

The injection pumps 10, which are driven by compression air connected to the compression chambers located in the middle of the cylinders.

Starting takes place with the glow plugs 29 switched on Compressed air and a starter injection pump, with the switching rod. The pressure oil or pressure water delivered in the circuit by the hydraulic pump drives a hydraulic motor or a counter-pressure free jet turbine.

The direct current purging takes place through the tangential inflow of the scavenging air with twist.

As a result, the exhaust gases are completely flushed out and there is also a tangential injection with a single-hole injection nozzle A good mixture formation is achieved in the air charge circulating in the same direction on the cylinder wall. The burning, which begins with the fuel particles facing the air, runs in the compression chamber from the outside to the inside and is therefore n-calibrated and complete at low injection pressure and lower air ratio.

The closed The engine is therefore suitable for various fuels . ·

Since with the opposing free pistons the surface - * / volume ratio is small, the heat losses are also small.

The proposed Thanks to the good mixture formation and the injection pumps with compression drive, engines are suitable for fast running and can also be equipped with an exhaust gas turbocharger with mitti. Pressures from 9 to 13 ■ work> 5 bar.

For proper functioning of the buffer chambers, the Buffer air autom. can be filled with charge air or compressed air. Each buffer piston 5 is therefore equipped with a charge air line 52 and a check valve for the buffer chamber P executed.

Because the accelerations of the free piston by the buffer pressures are smaller than due to the combustion pressures, the free

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Piston speeds lower when falling than when going down> At the decline that begins earlier; and ends later than the exit, the compression work is due to the kinetic energy, done by two free pistons.

To each cylinder is part of a complete injection pump 10 with ■ fuel pump; which are driven by the compression pressure.

The injection quantity is regulated automatically. via a rule mandrel and a control spring through the delivery pressure of the hydraulic pump, which is dependent on the load.

Except for the connections for the injection line 22, the fuel line 21, the compressed air 23 and the pressurized oil or Pressurized water 24, the connections for the starting compressed air 25 and the starting injection quantity are on the housing of the injection pump 26 arranged with check valves.

The limitation of the injection quantity in propulsion engines of ships and pumping is carried out by a control rod 16 located above the injection pumps, which controls the stroke of the control mandrels via thin bolts limited .

Switching the cylinder pairs on and off by switching the fuel pumps on and off requires the switching rod 18, which engages the pump piston of the fuel pumps via thin bolts and also switches the starting compressed air valves during the adjustment.

The starting air valve for the two lines 25 through the switch rod at standstill, closed and open during operation; the starter valves 55 of the Pump cylinders that are open when stopped are closed by the starting compressed air when starting.

Each pair of cylinders has two pressure air vessels 33 and two Suction air boiler 5 ^ · ·

The pressure air vessels are connected to compressed air via check valves 16 bar and are shut off at this pressure below by piston valves.

At a delivery pressure of "160 bar, the volume of a pressure air vessel would be about 30 times the delivery rate / stroke; the maximum pressure change at 160 bar is efcwa_ 10 % and at 80 bar only 5%.

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When a starting compressed air valve Λ2 is switched on , compressed air flows into both cylinders. At a pressure of 6 bar, the free pistons are almost in the middle position when the starter pump valves are open. This increases the pressure in the compressed air piston connections from 6 to 18 bar.

The starting injections, which are dependent on the pressure in the cylinders, take place in one cylinder at one pressure from 6 bar.

During the combustion, the two pistons are driven by the higher gas pressures accelerate outward and the compressed air in the other cylinder is free-piston via the piston connections compressed until the starter injection takes place at a pressure of around 8 bar.

Due to the greater acceleration that occurs during this combustion At the same time as the free pistons moved outwards, the accelerations of the inwardly moved ones via the compressed air piston connections Reinforced free piston.

With greater acceleration, the free pistons move outwards faster than inwards. If it began later, the decline expired earlier than the decline. After this initiation, the normal injections take place as soon as the compression pressures have risen to 30 bar. In addition, the starter piston valves, which are only open in the central position, and the starter pump valves are activated at higher gas pressure closed .

The starter injection pump driven by compressed air with two Pump piston and control slide is through lines with the injection pump connected to each cylinder.

Spring-loaded piston valves are arranged in these lines, which are closed at high and low pressures in the cylinders and only open in the middle positions at pressures 6 and 8 bar, respectively are .

By blocking the pump piston with; the piston valve can the start-up injection takes place only once in each cylinder when a pair of cylinders is switched on.

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On sheet A in Fig. A there is a longitudinal section through the injection pump and in Fig. b a longitudinal section through the fuel pump and the control mandrel shown for the injection pump. Fig. C and d show cross sections through the common housing.

In the case of the injection pump; which does not have a mech. The drive is the pump piston 70 via the spring-loaded piston 71 through the iCompression air driven and the injection valve used as a pressure valve.

In the case of the fuel pump, the spring-loaded pump piston 72 is also driven by the compressed air. The fuel is displaced by the spring during and after purging. The inlet opening of the injection pump controlled by the pump piston 70 is at low gas pressures during and long after the Flush open.

The injection is also throttled by the throttle nozzle 73 located behind the pump piston, so that the combustion pressures do not rise too high.

The injection quantity is regulated by the adjustment mandrel 74 behind the Fuel pump · and through the pressure relief valve 75 for the excess Fuel.

The piston 76, which is connected to the sail mandrel, is activated during the regulation . ^ the delivery pressure is printed against the Eegelfeder 77. The injection quantity is therefore dependent on the delivery pressure.

The injection pump also has the non-return valve .78 and the Connection for the starting injection quantity,. the connection for the starting compressed air on the channel to the compression chamber, the locking pin of the shift rod 18 for the fuel pump and the locking pin of the control rod 16 for the control mandrel of the injection quantity.

When starting, the internal positions of the free pistons are limited by the spring-loaded locking pins in the middle of the cylinders 16.

The starting compressed air valves 12 and the starting valves 35 of the pump cylinders remain closed during operation at gas pressures above 15 bar.

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On sheet 5 there is a longitudinal section in Fig. A and a in Fig. B Cross-section of the starter injection pump shown Starter injection pump consists of two pump pistons 80 which are connected to spring-loaded compressed air pistons 81, the Control slide 83 for the compressed air and the spring-loaded Piston valve 82, which trigger the starting injections in two cylinders when the bridge reaches 6 or β bar. When the compressed air is switched on, the control slide is adjusted by the switching rod 18 via a linkage. j

The control spool is changed over at the end of the stroke |

by means of a compressed air piston via the driver M. After the j

The two pump pistons are releasing the compressed air through the. ! Springs pushed back; the pump cylinder are in this case with · j When turning the spring-loaded spool is moved through a j rod by the shift rod 18 and held in place by the spring-j-loaded locking lever 84, ΐ overall to the lock lever by \ a compressed air piston at the end of the stroke from the locked position is pressed. After releasing the compressed air, the two will

Pump piston pushed back by the springs. 'j

According to sheet 6, this applies to the pressure and suction valves of the hydro | pump proposed nozzle cone valve from the valve body 90 with the inserted valve guide 91 »spring sleeve 92, valve spring 93 days the valve cone 94-

The valve cone with a wide valve seat, short. Stroke and low Gewi-e-Ht is activated by the valve spring and when the valve closes greatly accelerates the water pressure; the impact effect is dampened by the high pressure increase in the valve seat in this case water displacement proceeding with increasing splitting speed.

Behind the valve seat, the gap between the valve body and the spring sleeve is widened in the form of a nozzle, so that the “near gap speed” is greatly reduced without pressure loss.

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For the pressure valves 31 and the suction valves 32, cone valves are used Proposed with an enlarged nozzle behind the valve seat to prevent pressure losses at the high piston speeds don't get too big.

Since the gap speeds without pressure loss in the expanded If the nozzle behind the valve seat is greatly reduced when the pressure rises, the nozzle cone valve can be used for gap speeds of 20 to 30 m / s.

The delayed valve closing, which is inevitable with the short stroke times is cheaper with the pump pistons driven directly by the pre-piston than with a piston pump with crank drive, because here with backscattering of pressurized water the Preikolben without Frictional losses are driven and because when the water is displaced into the suction air vessel, the drive power as well actual delivery rate is smaller.

At piston speeds of 10 to 15 m / s, the pressure losses are 3 to 6 bar in a valve.

For a delivery pressure of 200 bar, this is the overall efficiency the hydraulic pump with direct free piston drive, for example. 0.97 to 0.94-.

For a quick opening of the suction valves and for a strong one • Acceleration of the water flowing into the pump cylinders at cylinder speeds of 10 to 15 m / s a pre-pressure of 5 to 6 bar required in the return line. The delayed opening of the pressure valves 31 takes place with strong Pressure rise in the pump cylinders very quickly. The height Peak pressure in the pump cylinders is not detrimental to the running of the machine because of the simultaneous driving force the free piston due to the gas pressure is much greater than the load on the pump piston.

As the impact of the light valve cone closing at a speed of up to 6 m / s is caused by the increasing gap speed water displacement is dampened when the pressure rises in the valve seat, the nozzle cone valves are also in larger version for * larger delivery rates at high delivery pressures suitable. "" "

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When regulating the injection quantity through the delivery pressure of the H.ydropunipe runs the prep. Motor faster under heavy loads than with low stress.

Since the speed of the hydraulic motor falls with increasing load, will the excess flow rate of the hydraulic pump in the pressure air vessel repressed. The increase in pressure associated with this increases the amount of fuel injected and the diesel engine runs faster. With a further increase in pressure and the amount of fuel injected, the hydraulic motor is activated When the pressure relief valve is open, it accelerates until it can displace the entire delivery rate of the hydraulic pump.

Delivery pressure, injection quantity and speed are therefore dependent on the load addicted .

Since the delivery pressure / the injection quantity and the If the engine speed falls to the idle limit, the previous __ beaten engine excluded.

The torque of the oil motor, which is dependent on the delivery pressure, has through the pressure air vessel has a balanced course.

The cylinder pairs are started up due to the oil drain at overpressure without interruption of the tensile force a smooth course. Short reductions in the speed of the oil motor to a standstill take place through an adjustable throttle valve in the pressure line. When a pair of cylinders is switched off, the hydraulic motor is idling for as long until its speed corresponds to the reduced delivery rate of the hydraulic pump. ;

A connection line with a check valve is provided for idling the hydraulic motor required between the pressure line and the oil cooler so that if the delivery rate is too small, the oil flow to the hydraulic motor is large enough is . *

The delivery pressure, speed and power are regulated when combining the hydraulic pump with one counter-pressure free jet turbine by adjusting the nozzle needles. -. When the nozzles are open, the hydraulic pump is idling.

Switching the diesel engine increases the power of the hydraulic engine the speed and, in the case of the back pressure free steel turbine, that Controlled torque.

Partial operation of the diesel engine also saves fuel when the load is low.

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By, the low. Pressure losses in the nozzle cone valves the efficiency of the hydraulic pump driven directly by free pistons at a delivery pressure of 200 bar and piston speeds from 10 to 15 m / s between 0.97 and 0.9 ^

With the high / efficiencies of the hydraulic pump and the back pressure free jet turbine and at the low. Heat losses of the two-stroke diesel engine with counter-rotating free pistons can result in an overall efficiency of the proposed Drive calculated from 0.4 to 0.45 will .

In addition, the simple design -without crank drive and Cylinder head at the high speed of a back pressure free jet turbine the power to weight ratio is much lower than that of a four-stroke diesel engine .

The proposed Drives are with complete mass balance, smooth running, favorable drive torque, simple control and of a simple, robust design suitable for driving. Vehicles, ships, conveyors, pumps, compressors and Electricity producer.

Claims (2)

j SUBSCRIBED Claims ΛI two-stroke diesel engine with counter-rotating free pistons «MOfe. lAemG & fr0mm & irimmfg — iim $ mim & $ ^ 4 ^ * + in which the stroke movement of the free piston is transferred in rotary motion by the pressure oil or water with a hydraulic motor or with a counterpressure free jet turbine delivered by a directly driven hydraulic pump, characterized in that two cylinders each ^: Have piston connections with water and compressed air, so that by displacing the compressed air, the acceleration pressures and the pressure losses are lower and the connecting channels arranged above are smaller and simpler. 2. Two-stroke diesel engine with counter-rotating free piston ^ jae * iP # W!? Ffl? · Mie * iÄi * ageäegeBaB # * ee ^^^ ·, characterized in that the pressure valves (31) and the suction valves (32) of the hydraulic pump as Nozzle cone valve, which is located behind the valve seat between the valve body and the. _: Spring sleeves have a nozzle-shaped widened gap so that the high gap speed is greatly reduced by increasing pressure without loss of pressure Two-stroke diesel engine with counter-rotating free pistons ^ βΑββίΜΜΒΒβΦοβ ^^ β ^ ίΙι ^^ »*** ^ * and according to claim 2 thereby characterized that the nozzle cone valves have a light, spring-loaded valve cone with short stroke and wide seat so that the impact of the valve cone, which is strongly accelerated by the water pressure, when closing by the strong pressure increase in the water displacement is damped with increasing gap speed in the valve seat. M-. Two-stroke diesel engine with counter-rotating free pistons Bmimm £ & umM & m * fi '& ** & ^e & ^ &**' ** ( ^l 't characterized in that the starter injection pump connected to the injection pumps by lines has two pump pistons (80), which are driven by compressed air via spring-loaded pistons (81) and displace the starting injection quantities at pressures of 6 to 8 bar in the cylinders through the lines opened by KoIbenschieberη (82) - delivery rate · has a steady course. SUBSCRIBED Two-stroke diesel engine with counter-rotating free pistons ammmUmti ^ ffSß ^ '^^ H ^ mmHA. according to claim. 3 ι characterized in that in every one "Shal ~ device the spring-loaded control slide (83) of the starter injection pump is adjusted with the switching rod so that the two pump pistons (80) are loaded with compressed air, and the injection quantities when the piston slide (82) is open and at the end of the stroke, by moving the locking lever (84), trigger the changeover of the spring-loaded control slide (83) for releasing the compressed air.